MLB instant replays up 35 percent from this time a season ago

We're only three weeks into the third year of Major League Baseball's expanded use of instant replay, but MLB's Replay Center has never been busier. Replay reviews are up 35 percent compared with this time last year. And Sunday saw 18 reviews in one day, the most ever.

All told, through Sunday, MLB had used replay to review 180 calls this season -- up from 133 through the corresponding date last year. If reviews continue at this rate, more than 1,650 calls would be decided by replay this season, up from 1,331 last season.

According to data compiled by Baseball Savant, the biggest difference between this season and last is a steep increase in manager challenges of baserunning calls. Last year, 46 percent of all replays were used to review forceouts and tag plays. This year, that percentage has jumped to 57 percent, with about 4 percent of the total coming from reviews of either takeout slides or the redefined "neighborhood play" under baseball's new sliding rules.

The other major reason for the increase in reviews is that managers are challenging calls more aggressively than ever before. Through Sunday, 92.8 percent of all reviews were initiated by manager challenges. That's up from 87 percent last year and 82.4 in 2014.

Home run replays are actually down this season. They represented 8 percent of all reviews last year, but have dropped to only 3 percent so far this year.

The 18 reviews Sunday topped the old "record" for most reviews in one day by three. The previous high of 15 occurred four times, twice in 2014 and twice in 2015. However, three of the reviews Sunday came in long extra-inning games in Washington and Arizona.

Despite complaints about the length of time which replay officials are taking to review calls, MLB says the average time of a review, from challenge to ruling, has remained relatively stable. The average time per review was 1 minute, 54 seconds through Sunday. It was 1 minute, 49 seconds at a similar stage of last season and 2:07 at the same juncture in 2014.